If he was familiar with those servers, he probably had a sense of how likely it would be that they would just "crash" out of the blue. I've seen Linux servers crash, but that's because they were setup by a dumbass and were doing all sorts of insane shit that kept filling up the disk and memory. If a server isn't doing anything stupid, it's pretty unlikely it's going to simply crash. He was working for criminals, and I think they said one guy was wanted for murder, so I can see why he'd be super suspicious.